The present invention relates to a ceramic electrostatic chuck with built-in heater or more particularly, to a ceramic electrostatic chuck with built-in heater used in the temperature elevation and lowering step in a semiconductor process.
While a heater by winding a metal wire is used heretofore for heating of a semiconductor wafer in the manufacturing process of semiconductor devices, a problem is involved therein by the contamination of the semiconductor wafer with metals so that proposals have been made for the use of an integral ceramic heater using a thin film of a ceramic as the heat generating body (see official publication of Japanese Patent Kokai No. 4-124076). Further, while an electrostatic chuck is used when a semiconductor wafer is heated in an atmosphere of a reduced pressure in order to fix the semiconductor wafer on the heater, resins as the material thereof are increasingly replaced with ceramics along with the trend toward higher and higher temperatures of the process (see official publication of Japanese Patent Kokai No. 52-67353 and official publication of Japanese Patent Kokai No. 59-124140) and, recently, a ceramic electrostatic chuck with built-in heater, which is an integral combination of such a ceramic heater and electrostatic chuck, is also proposed (see official publication of Japanese Patent Ko-kai No. 5-09876 and official publication of Japanese Patent Kokai No. 5-129210). And, since this ceramic electrostatic chuck with built-in heater basically has a structure in which different kinds of ceramics are bonded together, warping is caused due to the difference in their thermal expansion coefficients to decrease the chucking force so that a proposal has been made for a ceramic electrostatic chuck with built-in heater in which warping is prevented by using a substrate of a large thickness (see official publication of Japanese Patent Kokai No. 4-358074).
However, such a ceramic electrostatic chuck with built-in heater by the use of a substrate of a large thickness has a problem that the quantity of heat dissipated from the side surface of the substrate is so large as to produce a heat flow from the center to the side portion so that the temperature in the vicinity of the side portion is decreased not to give a uniform temperature distribution and the yield of acceptable devices manufactured therewith is decreased thereby.